1. Field of the Invention
The present general inventive concept generally relates to an image forming apparatus, a system-on-chip (SoC) unit, and a driving method thereof, and more particularly, to an image forming apparatus having a power-saving mode, an SoC unit, and a driving method thereof.
2. Description of the Related Art
Demands for low power of all electronic products have been gradually reinforced. If there are no actions against these demands, it will be impossible to sell electronic products due to the regulations in spite of their strong points of performances and prices.
Current specs of Energy Star require power consumption less than or equal to a range between 1 W and 2 W in a wait mode according to the types of devices. Power consumption of 1 W or less will be required even in a wait mode in which a network service is possible. In order to achieve this, all electronic companies utilize several methods.
Also, a device must not inconvenience a consumer depending on whether the device is in a low power mode or a normal operation mode.
In order to achieve a low power wait mode, most companies utilize a method of providing a service through a high-performance main central processing unit (CPU) in a normal mode, switching off unnecessary power of the high-performance main CPU and a system through a low power auxiliary CPU when the system goes into a wait mode under a specific condition, monitoring a service request through the low power auxiliary CPU, and when a user requests a service, applying power to the high-performance main CPU and auxiliary circuits to provide the service to the user.
For example, a conventional system uses a method of allocating power supply lines to first and second power domains, respectively, to manage a power source and then shutting off a power supply to the first power domain which does not need to operate in a low power mode service.
Therefore, if a condition of a change from a normal mode to a low power mode is satisfied, the conventional system performs a change to the low power mode, shuts off a power supply to the first power domain through a sub-controller, and goes into the low power mode.
In the conventional system, a main controller and a dynamic random access memory (DRAM) are turned off when the first domain is turned off. Thus, all data of the DRAM is lost, and the main controller is rebooted. Therefore, since a process of going from a power-saving mode into a normal mode according to a service request is performed equal to an initial system booting process, 10 seconds or more are required in conventional systems.
If a network link is gone out for 15 seconds or more after a printer requests printing from a network, an error message is displayed to a user.
If a multifunction peripheral does not respond to a button click of a panel, which is performed for a scan operation, within several seconds, a consumer doubts a performance of the multifunction peripheral in spite of the achievement of low power.